Temps were hovering around 70, and, up on the mountain, hepatica and mushrooms were blooming and wood frogs are calling for mates. Down on my deck, some unidentified little black bugs were biting the heck out of me as I sit enjoying a nice beer in my shirtsleeves. What a wonderful spring day — except it was December 27.
I can’t tell you how lovely, and wrong, the warm weather we had earlier this winter feels. I enjoyed that day in late December roaming around in the Appalachian woods (my backyard) photographing an array of lovely mushrooms and hepatica — white and delicate, with tri-lobed, fleshy leaves — and watching wood frogs jumping into the pond. I can’t help but note that winter had barely begun, and yet I was regularly seeing signs of spring a couple of weeks ago.
While a short thaw in winter will get wood frogs randy, I can’t remember when I heard them clacking and chuckling for mates as early as late December. Even the Virginia Department of Game and Inland Fisheries’ chart of anuran (frog and toad) phenology — cyclic and seasonal natural phenomena — lists the first mating periods as being the end of January, with wood frogs usually first out of the gate.
What ramifications do these unseasonably warm, and fluctuating, temperatures this time of year hold in store for the species that seem to be out of sync with the seasons? Will the hepatica blooms and the insects that normally pollinate them be out at the same time, or will the energy plants spend on these blooms just be wasted?
Some insects were certainly out in late December, and not just the ones on my deck (not gnats, but biting like them). Former sheriff and talented amateur photographer Larry Sherertz shared some photos with me of honey bees swarming his bird feeder on Christmas Day — specifically the feeder with corn. The temperature outside was 68 degrees, and more than 50 bees showed up, he says. They usually survive off of honey stored in their hive during the winter. Did they run out? Did the unseasonably warm weather draw them out? With little flower nectar or pollen available, were the bees attracted to the sugar in the ground corn in the birdfeed?
And if the wood frogs clacking for mates breed, will the eggs and larvae not only survive but develop properly? If the larvae are ahead of schedule, will the fully formed terrestrial young they morph into be able to survive and thrive?
Little is known about the possible effects of climate change on wild flora and fauna, but one recent study of wood frogs does show that even these versatile breeders are feeling the heat in terms of reproduction. The study was by Michael F. Benard, the George B. Mayer Chair in Urban and Environmental Studies and assistant professor of biology at Case Western Reserve University, and published in the journal Global Change Biology last spring. He compared winter weather records to the activities of more than 50,000 juvenile and hundreds of adult wood frogs over seven years.
Benard found that, after warmer winters, wood frogs breed earlier and produce fewer eggs. Although winter precipitation didn’t affect when the frogs bred, the researcher found that more eggs were produced in wet winters.
Breeding earlier didn’t seem to affect the survival or size of the larvae (tadpoles), but it did slow larval development. And the delay in larval development did not fully compensate for the earlier start of breeding: “For every two days earlier that breeding took place, the average date of metamorphosis was one day earlier.” Counterintuitively, Bernard points out that other studies have found that wood frogs that develop earlier can grow larger once they reach the adult stage and have a better chance of surviving, “suggesting that earlier breeding has beneficial effects on wood frog populations.”
It’s good to keep in mind that, while Benard’s study provides valuable information on how climate change may affect wood frogs, it’s only one study about one species that is relatively adaptable when it comes to temperature fluctuations in winter. Animals evolve to fit their climate, and change in climate has in the past generally taken place over thousands or millions of years, which gives species time to adapt and evolve. The current global warming trend is happening incredibly fast by comparison, and scientists have more questions than answers about how species, including Homo sapiens, will fare as the Earth continues to warm and weather patterns increasingly become less stable.
© 2016 Pam Owen